1. Field of the Invention
The invention relates to mechanisms for adjustably securing a seat to a vehicle.
2. Description of the Related Art
Conventional seats have been attached to vehicles such as lawn tractors in a variety of ways. Various devices have been provided having many mechanical parts that allow the operator to adjust the seat fore and aft. Tracks are provided for guiding the seat back and forth. To adjust the seat, the operator engages a lever which releases the seat from a locked position. The operator can then shift the seat fore and aft along the track. To again lock the seat in a fixed position, the operator then releases the lever, which causes a member to be engaged within an opening in a plate fixed to the vehicle. The plate has several openings such that the seat can be locked into a variety of different positions. These lever mechanisms have many parts, which increases the cost required to make and assemble the mechanism.
A more inexpensive type of mechanism for securing a seat to a vehicle provides a seat having bolts received within slots formed in members fixed to the vehicle. The bolts are positioned within slots, such that when the bolts are loosened the operator can slide the seat to the position that he desires. He then re-tightens the bolts to frictionally secure the seat in place. Many such conventional mechanisms provide painted metal parts that rub against each other as the seat is shifted fore and aft, thereby scratching the paint when the seat is adjusted. In an attempt to reduce such scratching, washers have been provided between the parts that rub against each other. It is known to provide mechanisms of this type with four bolts instead of two to more adequately secure the seat against pivoting about a vertical axis, as well as against shifting fore and aft. Some conventional mechanisms provide bolts that require the use of tools to tighten the bolts, while others provide bolts that can be tightened by hand.
During operation, the bolts used in this type of mechanism can become loosened. When loosened, the seat can rapidly shift forwardly or rearwardly during operation before the operator notices that the bolts are loose. Many such mechanisms provide slots that are inclined downwardly toward the front such that as a shorter operator adjusts the seat forwardly to reach the controls he will also be lowering the seat. Similarly, taller operators will shift the seat rearwardly and upwardly in the slots. When the bolts become loosened in these inclined slots, bumpy terrain and the weight of the operator may cause the seat to suddenly shift forwardly and downwardly within the slots. Such a sudden shifting of the seat upon which the operator is sitting may cause his hands or feet that are manipulating the controls to suddenly jerk. Sudden motion of the seat base may prevent the operator from performing vehicle operations requiring delicate or precise control.
It would be desirable to provide a mechanism for securing a seat to a vehicle to prevent fore and aft shifting of the seat, and also prevent pivoting of the seat about a vertical axis. It would be desirable for such a mechanism to be simple and comprised of few parts, while being inexpensive to manufacture and assemble. The mechanism should be capable of being manufactured by injecting plastic into a mold. A mechanism made of plastic material would be desirable, since plastic parts will not scratch painted metal parts as much as a mechanism made of metal will. Such a mechanism should allow the operator to adjust the seat fore and aft to the particular position he finds most comfortable. It would be desirable for such a mechanism to be adjustable without the use of tools. Also, it would be desirable for such a mechanism to allow the operator to sense when the seat is becoming unsecured during operation. The operator could then tighten the seat before it shifts suddenly.